1. Field of the Invention
The present invention concerns a method and device for the switching of a packet between a transmitter and receivers.
It should be noted that, hereinafter, the term `subscriber` will be often used in preference to the term `receiver` and the term "addressee" will represent a subscriber designated to receive a message contained in the packet.
This document makes use of the notions of the "main trunk route", arrows and arrowed packets (also called self-routing datagrams) in the field of packet transmission. In the rest of this document, including the claims, the term "transmission" implies both the transmission and the distribution of data.
A transmission of data is said to be done by a main trunk route or along a main trunk route when the transmission of data is done in travelling along a path with branching out points on this path, where the data are transmitted and distributed locally.
An arrow is a code number placed in a packet and used, for example, by a switch to direct the packet towards one of its outputs: this arrow is "plucked out", i.e. withdrawn from the packet as soon it has been used. Packets provided with arrows, also called arrowed packets, have been designed to achieve a point-to-point link, i.e. a link between a transmitter and a single receiver; the arrows with which the packet is provided when it is prepared indicate the path to be followed, in the network, between the transmitter and the receiver. The arrowed packet method enables very fast switching, and therefore lends itself to every type of application such as telephony, real time data transmission, etc. Packets of this type are used in the European patent application No. 0006798.
Until now, owing to the very fact of their initial design, arrowed packets have not been used for transmission to a large number of addressees since, as noted above, they were planned only for point-to-point links.